Post-deflection color tube utilizing secondary emission



- April 1965 MASAO INABA ETAL 3,179,841

POST-DEFLECTION COLOR TUBE UTILIZING SECONDARY EMISSION Filed July 11, 1962 I 2 FLA/V! I Hi" PLANE R VIDEO 1 AMP 7: VOLTAGE RATOE 14; v .DE'FLE A UD/ 0 DE); /0/

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INVENTORS MAS/l0 M/ABA BY ,(64 fdl/H/AO IVOMU/FA United States Patent 3,179,841 POST-DEFLECTION COLOR TUBE UTILIZING SECONDARY EMISSION Masao'lnaba and Katsuhiko Nornura, Tokyo, Japan, assignors to Nippon Electric Company Limited, Tokyo,

Japan Filed July 11, 1962, Ser. No. 209,178 Claims priority, application Japan, July '17, 19;61, 36/ 25,602 7 Claims. (Cl. 315-13) This invention relates to television receiving facilities and more particularly to receiving facilities for use in color television systems wherein the receiver facility employs a novel cathode-ray tube and associated peripheral circuitry for receiving and reproducing an improved full color picture under control of video signals of the NT SC system. Prior art color receivers presently found in wide spread use, are of the so-called shadow mask type which is comprised of a fluorescent screen having fluorescent elements representing the primary colors wherein each primary color has a corresponding electron gun associated therewith. This arrangement thereby provides a color breakdown into the three primary colrs which, blended together in any combination, provide the ultimate color picture produced by the receiver facility. Color cathode-ray tubes of the above mentioned type, however, have been found to have the following significant defects:

Shadow mask tubes are provided with a metal place spaced apart from the phosphorus screen, having a large number of holes wherein the holes are aligned with one of the triads whereby each hole is aligned with one of the triad (triangular dart) arrangements of the phosphorescent primary colors. Since the impinging electrons must pass through this mask in order to illuminate the screen the number of electrons hitting the mask and thereby failing to contribute to the luminance of the picture significantly limits the efliciency of the electron beam and the brightness of the picture. I

The c'ritcal geometric configuration of prior art shadow mask tubes may have the color purity of the color reproductions significantly affected by the earths magnetic field found in the particular environment in which the color receiver is located.

The shadow mask tubes arecomprised of three separate electron beams emanating from three associated electron guns. An extremely complex magnetic field generating facility is required in order to maintain the convergence of these three electron beams.

In order to adequately accelerate the electrons in each electron beam it becomes necessary to have an extremely high voltage power source, having extremely constant voltage regulation characteristics.

The geometric considerations of the shadow mask tube are so extremely critical that the cost of the shadow mask tube is quite substantial.

In order to overcome the aforementioned disadvantages of the shadow mask tube complicated electron circuitry is necessary in order to provide satisfactory operation thereof. The complex circ'uitry thereby has an adverse eftect on the stability of such color television receivers. l

The device of the instant invention is so constructed as to completely avoid the need for complex electron beam convergence of the type described immediately above and further eliminates any effect of the earths magnetism upon the tube operation, while providing perfectly stable operation thereof, while at the same time substantially simplifying the overall design of the receiver tube.

The device of the instant invention is comprised of a color receiving tube having an envelope housing an electron gun assembly at. the neck of the tube and a novel 3,179,841 Patented Apr. 20, 1965 "ice screen arrangement at the face of the tube enevlope at a spaced distance away from the electron gun structure.

The screen assembly is comprised of plurality of phosphorescent or fluorescent strips capable of generating light representative of the three primary colors, wherein the strips are-arranged so as to be substantially of parallel alignment. A metallic or conductive grid arrangement is provided for each primary color element wherein each grid is electrically insulated from the remaining grids. A secondary emission membrane is positioned in'the tube envelope between the electron gun and the tube screen face. 'The secondary emission membrane functions to release electrons which are directed towards the phosphorescent primary color strips which secondary emission is caused by the electron beam'from th'e tube electron gun impinging upon the membrane surface.

In order that the secondary emission electrons strike the appropriate phosphorescent strip, circuitry is provided within the receiver facility and is associated with the color receiver tube for generating voltages at the base of each phosphorescent primary color strip which voltage signals are of such polarity as to selectively attract or repel electrons aimed towards the phosphorescent strip connected to the voltage sources. These alternating voltage sources are maintained in a pre-determined phase relationship relative'to one another, and their polarities are determined ture of the scene transmitted from the transmitter location which is far superior to color pictures produced by prior art devices, while at the same time minimizing the complexity of the color receiver facility.

The receiver tube of the instant invention is constructed so as to have three separate electron guns, each being associated with one of the primary colors. Circuitry is provided in the receiver facility which is connected with the electron guns associated therewith in order to compensate for the intensities of the electron beams emanated from each electron gun so as to produce an overall constant amplitude beam, the intensity of which is determined by only one composite control signal and which is employed to generate a color picture duplicating the picture transmitted by the remote transmitter facility under control of the novel color tube screen assembly.

It is therefore one object of this invention to provide a receiver tube for a color receiver facility, having novel means for controlling the impingement of'electrons upon the primary color fluorescent elements.

Still another object of the instant invention is to provide a color receiver tube of cold cathode construction for color receiver facilities. i '7 Another object of this invention is to provide a color receiver tube for color receiver facilities having a novel cold cathode construction and employing a secondary emission membrane adapted to supply electrons which impinge upon the primary color elements of the tube face.

' Another object of this invention is to provide a color receiver tube for a color receiver facility having a separate electron gun associated with eachof the primary colors being received wherein means are provided for converging the beams from each'electron gun into a unitary beam. l v i a Another object of this invention is to provide a color receiver facility comprised of a novel color receiver tube, having a plurality of primary color elements arranged on the tube face and having electronic circuitry electrically connected with the primary color elements for controlling the attraction and/or the deflection of electrons upon the associated primary color elements. V V

These and other objects will become apparent upon consideration of the accompanying description and drawings, in which:

FIGURE 1 is an elevation or cross-section view of a color receiver tube designed according to this invention.

FIGURE 2 is an elevation or view, partly in cross-section and partly schematic, showing a portion of the color receiver tube of FIGURE 1 greatly enlarged, and further showing the electronic circuitry associated therewith.

FIGURE 3 is a perspective view of the electron gun employed in the color receiver tube of FIGURE 1 showing the beam convergence means employed in the instant invention.

FIGURE 4 is a part schematic, part block diagram arrangement of the color receiver facility, designed according to the principles of the instant invention.

Referring now to the drawings, FIGURE 1 shows a color tube designed according to the principles of the instant invention, and having a glass envelope 11 provided with a base 12 having suitable pin members 12a, each associated with various electrodes within the tube envelope 11, and further provided for facilitating electrical connections between the various electrodes and the associated electronic circuitry to be more fully described. An electrongun arrangement 13 is provided in the neck portion of the tube envelope 11, and is provided with three separate cathode elements 13a, 13b and 13a. The electron gun 13 has its elements 13a through 130 electrically connected in any suitable manner (not shown) to the pin connections 12a of the base 12. The separate elements of the electron gun 13 operate to produce an electron beam 14, which is employed to initiate energization of the primary color fluorescent elements in a manner to be more fully described.

Also provided within the tube envelope 11 and positioned at the face end 11a thereof, is a cold cathode membrane 15 which is positioned so as to be substantially concentric With the tube face 11a. Positioned within the tube envelope 11 and to the left of tube face 11a and the right of the cold cathode member 15 is a fluorescent screen 16, which is comprised of a plurality of dots of fluorescent elements to be more fully described in connection with the description of FIGURE 2, which elements are provided so as to fluoresce or glow, upon the impingement of electrons. The cold cathode member 15 operates in such a manner as to emit electrons upon the impingement of the electron beam 14 upon the left hand surface of member 15. These electrons which .form the secondary emission phenomenon are suitably accelerated in the direction of the screen 16 in order to impinge upon the appropriate primary color element or elements. This arrangement permits the highly accelerated electrons from the electron beam 14 to be prevented from reaching the fluorescent screen 16 so as to cause any damage, while at the same time providing an adequate electron beam moving at a suitable velocity in order to satisfactorily illuminate the fluorescent screen 16. The individual primary color fluorescent elements are arranged substantially as shown in FIGURE 2 wherein the elements 17, 17' and 17" are of a red fluorescent material. The elements 18, 18' and 18" are of a green fluorescent material and the elements 19, 19 and 19" are of a blue fluorescent material. The elements are positioned so that the red fluorescent elements 17 through 17" lay in a first plane and the elements 18 through 18" and 19 through 19 lay in second and third planes, wherein the first, second and third planes are substantially parallel to one another and being interspersed in an alternating fashion spaced a predetermined distance apart. While it is possible to place all of the elements 17 through 17", 18 through 18" and 19 through 19" in a single plane, such as, for example, the first plane, it has been found that the arrangement of FIGURE 2 has the advantage of eliminating discharge of the elements when they have been impinged by the electron beam from the cold cathode structure. In order to insure suitable electron emission from the cold cathode member 15, it has been found that satisfactory results are obtained by charging the color tube envelope 11 with an extremely small measured quantity of a suitable rare gas.

The phosphorescent elements are positioned as can be seen in FIGURE 2 so that for the vertical array the arrangement is red, green, blue, red, green, blue, etc. With respect to the horizontal array of the phosphorescent elements, either one of two possible arrangements may be employed. As a first possibility, the elements 17, 18 and 19 may be elongated ribbons extending the entire width of the screen 16, thereby providing a horizontal layer arrangement, or the same array which exists in the vertical direction may be provided in the horizontal direction; that is, individual dots of fluorescent elements may be aligned in the horizontal direction in the same array as is shown in FIGURE 2. Each red fluorescent element 17 through 17 is constructed to be at the same voltage level by means of the conductive bus 37, which is electrically connected to the base of each red element 17 through 17". In a like manner green and blue elements 18 through 18" and 19 through 19 respectively are provided with respective busses 38 and 39. The composite screen employing this design, thereby takes on the form such that the individual busses 37, 38 and 39 actually take on the form of a fine metallic grid or net, wherein each primary fluorescent layer is provided with and electrically connected to, an associated metallic net, or grid, each of said grids being insulated from one another. The metallic net is connected at one end to suitable alternating voltage sources which are shown schematically in FIGURE 2 wherein the sources 21, 22 and 23 are connected respectively to the busses 37, 38 and 39. The opposite terminals of the alternating voltage sources are connected to a common terminal 40 to which an accelerating voltage source E is connected. The opposite end of the accelerating constant voltage source 14' is connected to ground potential 41. The voltage sources 21 to 23 all operate at the same frequency wherein the alternating voltages e e and e generated therefrom differ from one another by a pre-determined phase relationship as will be more fully described.

As mentioned previously, the electron beam 14 emitted from electron gun 13 is suitably deflected and accelerated by means not shown, causing the electron beam to collide against the left surface of the cold cathode structure 15'. The impact energy of the electrons in the electron beam is imparted to the cold cathode structure 15 thereby initiating cold electron emission. The electrons emitted from the cold cathode structure 15 due to the bombardment are attracted to the fluorescent elements of the screen 16 which have the highest voltage potential in the region of the electron beam, which attracting voltage potential will be of some level greater than the potential at terminal 40 of the power source 14.

On the other hand, when the potential of the fluorescent elements is lower than the voltage level at terminal 40, the electron beams in the immediate region of the fluorescent element at this lower voltage potential are repelled. It should be noted that these two phenomenon hold true since the cold cathode structure 15 is at the same potential as terminal 40, cold cathode structure 15 being connected at terminal 49 by means of conductor 15a.

Considering alternating voltages e e and e for example, if it is assumed that only e is positive, while e and e are negative, the electrons emitted from the cathode structure 15 impinge upon and therefore excite only the red fluorescent elements 17, 17' and 17", and not the green and blue fluorescent elements 18 through 18 and 19 through 19". Thus, by controlling the voltage levels at the basis of the color elements, it is possible to accurately control the receiver tube color selection.

alternating voltage 2 is positive, it should be obvious that any color may be produced by a combination of exciting the three primary color elements to varying degrees by means of controlling the voltage levels of voltage sources 21 through 23, so as to form any such color combination.

The operation of the color receiver tube from the moment that the electron beam 14 impinges upon the cold cathode structure 15 is as follows:

The electron beams emitted from the cold cathode structure 15 due to the secondary emission phenomenon, are accelerated towards the tube screen 16 in a direction controlled by the voltage potentials of the various primary color fluorescent elements. As the cathode-ray tube is charged with an extremely small quantity of rare gas, in order to promote the electron emission of the cold cathode, the gas in the region of the cold cathode becomes ionized, the ionized particles surround the advancing electron beam. The electron beam is affected by the ionized gas and becomes automatically focused as a result of the interaction between these particles. In this manner the rare gas introduced into the cathode-ray tube 10 not only activates and promotes electron radiation from the cold cathodes structure 15, but also focuses the electron beams radiated from the cold cathode structure.

The electron gun 13 employed in the cathode-ray 10 in FIGURE 1 is so constructed that the electron beams radiated from all the electron guns 13a through 13c converge so as to form one beam 14. As shown in FIGURE 3, the electron guns 24, 25, and 26 are arranged along the surface of a cone, having an axis along the surface of a cone 45, which has an axis collinear with'the line 14 of FIGURE 1, representing the direction of travel of the electron beam. The electron guns 24 through 26 are angularly positioned around the cone 45 so that the left hand ends, together with the center point 46 of the base of cone 45 form three straight lines or radii 24, 25' and 26' which are substantially angularly spaced 120 apart from one another and which are substantially equal in length. In this arrangement, the distance from the right hand ends of each electron gun 24 through 26 to the point of convergence 4'7 along the axis 14 of cone 45 are cuitry (not shown) providing for converging the three separate beams into a single unitary electron beam.

FIGURE 4 shows a receiver facility 100', employing the color receiver tube of the instant invention. The receiver facility .100 is comprised of an antenna 101 for picking up color television signals from remote transmitters which is impressed upon a tuner stage 102, which is employed .to amplify the received signals, select the desired carrier and perform at least one frequency conversion operation on the received modulated carrier signal. The output of the circuitry 102 is impressed upon an IF amplifier 103. One output terminal of IF amplifier 103 is impressed upon the detector circuit 105 which takes the voice information from the demodulated carrier and impresses it on the input terminals of speaker 106 which converts the electrical audio signals into the well known mechanical vibrations in order to produce the sound transmitted with the picture information. The second output terminal of IF'amplifier v10 3 is connected to the input terminal of detector circuit 104 which performs a detector function and which amplifies the detected video signals. A subcarrier signal generator 157, is'equipped with an oscillator (not shown) adapted to generate a frequency of 3.58 mc., for example, which signal is in a constant phase relationship with the color signal component of the composite video signal. The oscillator signal is heat against the color signal in a manner to be more fully described. A sync pulse separator circuit 108 is provided for separating the synchronizing pulses from the composite video signal impressed upon the input terminal circuit 108 from one output terminal of detector circuit 104. The synchronizing pulses are processed by circuit 108 and impressed upon the horizontal and vertical deflection generequal. The yoke member 28 is connected to suitable cirating circuit 109, which impresses the suitable deflection signals upon the deflecting yokes 116 and 117 of the cathode-ray tube .118. A high voltage generator circuit 110 is provided for impressing the necessary accelerating voltages and other suitable voltage levels upon the horizontal and vertical deflection generating circuit 109, the alternating voltage generator (to be more fully described) and the color receiver tube 118. The video amplifiers 112 through 114 are connected to the output terminal of detector circuit 104 and impress their output voltages upon the respective cathodes of the electron gun structure of color receiver tube 118. The video amplifiers 112 through 114 are designed to have specific frequency characteristics in order to correct the red, green and blue video signals impressed upon the amplifiers in a manner to be more fully described. Circuit 115 is the alternating voltage generator which is employed for breaking up the color signal developed by the sub-carrier signal generator 107 into the three phase source comprised of alternating voltages e e and e which are electrically connected to the fluorescent elements in a manner previously described with respect to FIGURE 2. In order to obtain the required peak value for the alternating voltages the high voltage generated by the circuit 110 raises the voltage levels of the control voltages e through e in order to provide for acceleration of electrons from the cold cathode structure 15 to the fluorescent screen elements 17 through 19, as was previously described. When the receiver facility 100 shown in FIGURE 4 is employed to receive color television signals in conformity with the NTSC system, the following design considerations are encountered.

Since the ratio between the brightness component and the difference signal component of the received video composite signal, which signals are produced by the NTSC matrix, are different for each primary color, amplifiers 112 through 114 aredesigned to correct this difference by having variable insertion losses in the frequency range of the chroma component which range is approximately 2.5 to 4.2 me. and which is occupied by the color sub-carrier of 3.58 mc., and the side band component thereof for the insertion loss of the range 0 to 2.5 mc. On the other hand, the absolute loss is so designed as to correct the luminous efliciency of each fluorescent element.

The color selection voltages e e and e are chosen in relation to the phases of the color difference signals in the NTSC system in the following manner:

If it is assumed that the NTSC chrominance signal e is represented by the following equation:

where E E and E are the voltages representing the red, blue and green signals respectively, which are received by the color receiver facility. When the synchronous detector .107 has a constant relative phase of 90 for the red colora'relative phase of 0 and is given by Equation 4:

when the green color-difference signal is developed by a synchronous detector, the phase relationship of the green color-diflerence signal'is obtained by using Equation 5 E -E =O.51(E E )O.l9(E E (5') Using Formulas l and 5, therefore, we obtained Equation 6:

e =E sin (wt-P236") (6) The values 6 e and e;; of the alternating voltages e c and (2 are substantially of the same magnitude. Thus by obtaining the phase relationships set forth in Equations 3, 4 and 6 above, the instantaneous magnitudes of the voltages impressed upon the basis of the red, green and blue phosphor elements comprising the cathode-ray tube screen, as well as the polarities of these instantaneous values, accurately and reliably control the impingement of the electron beam emanating from the secondary emission cathode upon the appropriate phosphor elements so as to successfully reproduce the desired colors upon the color receiver tube facility. Thus it can be seen that the alternating voltages generator source 115 for generating the 3 phase related voltages maintains the phase relationships set forth in Equation 3, 4 and 6 given above, while the video amplifiers 112 through 114 are adjusted so as to correct the difference signal components.

The color receiver facility designed in accordance with the principles described above has the following advantages:

The electron beams exciting the fiuorescent primary color elements are emitted from the cold cathode construction positioned in the immediate neighborhood of the fluorescent elements. While the color selection is conducted at the screen position of the color receiver tube, the overall structure thereby becomes extremely stabilized and thereby unaffected by external magnetic fields.

Since no shadow mask is either necessary nor useful in the present embodiment, the efliciency of the electron beams are high, thereby producing an extremely bright picture.

Since the color receiver tube of the invention employs a cold cathode construction and the electron beams emitted therefrom excite definite fluorescent primary color elements, the design problem are simplified substantially with respect to the high voltage power source necessary for accelerating electron beams and for actuating the color receiver tube deflection circuitry.

Since the three beams from the separate electron guns provided in the receiver tube envelope are converged into a single unitary beam, no complex convergence operation is required to converge these three beams therefore the operation of the unit becomes very stable. The dynamic convergence problems are referred to more specifically in the reference Colour Television, written by P. S. Carnt and G. B. Townsend, copyright 1961, and published in England by the Chapel River Press, Ltd., which reference also provides an elaborate explanation of the NTSC color system. The description therein being incorporated herein by reference thereto.

As no high geometric accuracy is required for the production of the cathode-ray color tube, the production costs are decreased considerably, thereby reducing the overall cost of the color television receiver.

Aside from the NTSC color system it should be noted that the color television receiver using the cathode-ray tube employing the principles of the instant invention works equally well in sequential color systems such as the point, line and field sequential systems, and further'may be employed in stereoscopic television systems.

Although there has been described a preferred embodi ment of the novel invention, many variations and modifications will now be apparent to those skilled in the art, therefore, this invention is to be limited, not by the specific dis closure herein, but only by the appending claims.

The embodiments of the invention in which an exclusive privilege or property is claimed are defined as follows:

1. Image reproducing means for generating a true-color image comprising a tube envelope; first and second groups of fluorescent elements arranged along the face of said envelope; said first group being comprised of minute elements arranged at spaced intervals and being adapted to emit a primary color when suitably excited; said second group being comprised of minute elements arranged at spaced intervals and being adapted to emit a primary color different from that of the first group elements when suitably excited, the elements of said first and second groups lying substantially in a plane and being arranged in an alternating fashion; first and second electronic control means connected to the elements of said first and second groups, respectively, for generating first and second alternating voltages, respectively; the elements of said first and second groups being electrically insulated; a substantially fiat cathode member positioned in said envelope in close proximity to said tube face; means comprising at least rst and second electron guns for generating first and second electron beams, respectively; means for converging said first and second electron beams into a single electron beam; deflection means controlling said single beam to race a regular pattern upon said cathode member; said cathode member being adapted to undergo secondary emission of electrons when bombarded by said single electron beam; said first and second control means influencing the electrons of said secondary emission to direct said secondary emission electrons to impinge upon selected ones of said elements of said first and second groups to generate the desired color combinations of the image being produced.

2. Image reproducing means for generating a true-color image comprising a tube envelope; first and second groups of fluorescent elements arranged along the face of said envelope; said first group being comprised of minute elements arranged at spaced intervals and being adapted to emit a primary color when suitably excited; said second group being comprised of minute elements arranged at spaced intervals and being adapted to emit a primary color different from that of the first group elements when suitably excited, the elements of said first and second groups lying substantially in a plane and being arranged in an alternating fashion; first and second electronic control means connected to the elements of said first and second groups, respectively, for generating first and second alternating voltages, respectively; the elements of said first and second groups being electrically insulated; a substantially fiat cathode member positioned in said envelope in close proximity to said tube face; means comprising at least first and second electron guns for generating first and second electron beams, respectively; means for converging said first and second electron beams into a single electron beam; deflection means controlling said single beam to trace a regular pattern upon said cathode member; said cathode member being adapted to undergo secondary emission of electrons when bombarded by said single electron beam; said first and second control means influencing the electrons of said secondary emission to direct said secondary emission electrons to impinge upon selected ones of said elements of said first and second groups to generate the desired color combinations of the image being produced, said tube envelope containing a small measured quantity of rare gas to aid electron radiation as well as focusing said secondary emission electrons.

3. Image reproducing means for generating a true-color image comprising a tube envelope; first and second groups of fluorescent elements arranged along the face of said envelope; said first group being comprised of minute elements arranged at spaced intervals and being adapted to emit a primary color when suitably excited; said second group being comprised of minute elements arranged at spaced intervals and being adapted to emit a primary color different from that of the first group elements when suitably excited, the elements of said first and second groups lying substantially in a plane and being arranged in an alternating fashion; first and second electronic control means connected to the elements of said first and second groups, respectively, for generating first and second alternating voltages, respectively; the elements of said first and second groups being electrically insulated; a substantially flat cathode member positioned in said envelope in close proximity to said tube face; means comprising at least first and second electron guns for generating first and second electron beams into a single electron beam; deflection means controlling said single beam to trace a regular pattern upon said cathode member; said cathode member being adapted to undergo secondary emission of electrons when bombarded by said single electron beam; said first and second control means influencing the electrons of said secondary emission to direct said secondary emission electrons to impinge upon selected ones of said elements of said first and second groups to generate the desired color combinations of the image being produced, said cathode member being a cold cathode construction.

4. Image reproducing means for generating a true-color image comprising a tube envelope; first and second groups of fluorescent elements arranged along the face of said envelope; said first group being comprised of minute elements arranged at spaced intervals and being adapted to emit a primary color when suitably excited; said second group being comprised of minute elements arranged at spaced intervals and being adapted to emit a primary color dilferent from that of the first group elements when suitably excited, the elements of said first and second groups lying substantially in a plane and being arranged in an alternating fashion; first and second electronic control means connected to the elements of said first and second groups, respectively, for generating first and second alternating voltages, respectively; the elements of said first and second groups being electrically insulated; a substantially flat cathode member positioned in said envelope in close proximity to said tube face; means comprising at least first and second electron guns for generating first and second electron beams, respectively; means for converging said first and second electron beams into a single electron beam; deflection means controlling said single beam to trace a regular pattern upon said cathode member; said cathode member being adapted to under go secondary emission of electrons when bombarded by said single electron beam; said first and second control means influencing the electrons of said secondary emission to direct said secondary emission electrons to impinge upon selected ones of said elements of said first and second groups to generate the desired color combinations of the image being produced, said first and second control means generating alternating voltages distinguishable from one another by a predetermined constant phase angle.

5. Image reproducing means for generating a true-color image comprising a tube envelope; first and second groups of fluorescent elements arranged along the face of said envelope; said first group being comprised of minute elements arranged at spaced intervals and being adapted to emit a primary color when suitably excited; said second group being comprised of minute elements arranged at spaced intervals and being adapted to emit a primary color dilferent from that of the first group elements when suitably excited, the elements of said first and second groups lying substantially in a plane and being arranged in an alternating fashion; first and second electronic control means connected to the elements of said first and second groups, respectively, for generating first and second alternating voltages, respectively; the elements of said first and second groups being electrically insulated; a substantially fiat cathode member positioned in said envelope in close proximity to said tube face; means comprising at'least first and second electron guns for generating first and second electron beams, respectively; means for converging said first and second electron beams into a single electron beam; deflection means controlling said single beam to trace a regular pattern upon said cathode member; said cathode member being adapted to undergo secondary emission of electrons when bombarded by said single 1% electron beam; said first and second control means influencing the electrons of said secondary emission to direct said secondary emission electrons to impinge upon selected ones of said elements of said first and second groups to generate the desired color combinations of the image being produced, said first and second control means generat ng alternating voltages distinguishable from one another by a predetermined constant phase angle, said first.

and second alternating voltages being of the same operating frequency.

6. Image reproducing means for generating a true-color image comprising a tube envelope; first and second groups of fluescent elements arranged along the face of said envelope; said first group being comprised of minute elements arranged at spaced intervals and being adapted to emit a primary color when suitably excited; said second group being comprised of minute elements arranged at spaced intervals and being adapted to emit a primary color different from that of the first group when suitably excited; the elements of said first and second groups lying substantially in a plane and being arranged in an alternating fashion; first and second electronic control means connected to the elements of said first and second groups, respectively, for generating first and second alternating voltages; means comprising at least first and second electron guns for generating first and second electron beams, respectively; means for converging said first and second beams into a single electron beam; deflection means controlling said single beam to trace a pattern upon said envelope face; said first and second control means influencing electrons moving toward said envelope face to impinge upon selected ones of said elements of said first and second groups for generating the desired color combinations of the image being produced.

7. Image reproducing means for generating a true-color image comprising a tube envelope; first and second groups of fluorescent elements arranged along the face of said envelope; said first group being comprised of minute elements arranged at spaced intervals and being adapted to emit a primary color when suitably excited; said second group being comprised of minute elements arranged at spaced intervals and being adapted to emit a primary color different from that of the first group when suitably excited; the elements of said first and second groups lying substantially in a plane and being arranged in an alternating fashion; first and second electronic control means connected to the elements of said first and second groups, respectively, for generating first and second alternating voltages; means comprising at least first and second electron guns for generating first and second electron beams, respectively; means for converging said first and second beams into a single electron beam; deflection means controlling said single beam to trace a pattern upon said envelope face; said first and second control means influencing electrons moving toward said envelope face to impinge upon selected ones of said elements of said first and second groups for generating the desired color combinations of the image being produced, said tube envelope containing a small measured quantity of rare gas to aid electron radiation as well as focusing electrons moving toward said envelope face.

References Cited by the Examiner UNITED STATES PATENTS 1/59 Charlton 315 21 3/62 Burdick 315-12 

1. IMAGE REPRODUCING MEANS FOR GENERATING A TRUE-COLOR IMAGE COMPRISING A TUBE ENVELOPE; FIRST AND SECOND GROUPS OF FLOURESCENT ELEMENTS ARRANGED ALONG THE FACE OF SAID ENVELOPE; SAID FIRST GROUP BEING COMPRISED OF MINUTE ELEMENTS ARRANGED AT SPACED INTERVAL AND BEING ADAPTED TO EMIT A PRIMARY COLOR WHEN INTERVALS AND BEING ADAPTED TO GROUP BEING COMPRISED OF MINUTE ELEMENTS ARRANGED AT SPACED INTERVALS AND BEING ADAPTED TO EMIT A PRIMARY COLOR DIFFERENT FROM THAT OF THE FIRST GROUP ELEMENTS WHEN SUITABLY EXCITED, THE ELEMENTS OF SAID FIRST AND SECOND GROUPS LYING SUBSTANTIALLY IN A PLANE AND BEING ARRANGED IN AN ALTERNATING FASHION; FIRST AND SECOND ELECTRONIC CONTROL MEANS CONNECTED TO THE ELEMENTS OF SAID FIRST AND SECOND GROUPS, RESPECTIVELY, FOR GENERATING FIRST AND SECOND ALTERNATING VOLTAGES, RESPECTIVELY; THE ELEMENTS OF SAID FIRST AND SECOND GROUPS BEING ELECTRICALLY INSULATED; A SUBSTANTIALLY FLAT CATHODE MEMBER POSITIONED IN SAID ENVELOPE IN CLOSE PROXIMITY TO SAID TUBE FACE; MEANS COMPRISING AT LEAST FIRST AND SECOND ELECTRON GUNS FOR GENERATING FIRST AND SECOND ELECTRON BEAMS, RESPECTIVELY; MEANS FOR CONVERGING SAID FIRST AND SECOND ELECTRON BEAMS INTO A SINGLE ELECTRON BEAM; DEFLECTION MEANS CONTROLLING SAID SINGLE BEAM TO TRACE A REGULAR PATTERN UPON SAID CATHODE MEMBER; SAID CATHODE MEMBER BEING ADAPTED TO UNDERGO SECONDARY EMISSION OF ELECTRONS WHEN BOMBARDED BY SAID SINGLE ELECTRON BEAM; SAID FIRST AND SECOND CONTROL MEANS INFLUENCING THE ELECTRONS OF SAID SECONDARY EMISSION TO DIRECT SAID SECONDARY EMISSION ELECTRONS TO IMPINGE UPON SELECTED ONES OF SAID ELEMENTS OF SAID FIRST AND SECOND GROUPS TO GENERATE THE DESIRED COLOR COMBINATIONS OF THE IMAGE BEING PRODUCED. 